Evaluation of the alkalinity stress tolerance of three Brassica rapa CAX1 TILLING mutants

Alkalinity is an important environmental factor that affects crop production and will be exacerbated in the current climate change scenario. Thus, the presence of carbonates and high pH in soils negatively impacts nutrient assimilation and photosynthesis and causes oxidative stress. A potential strategy to improve tolerance to alkalinity could be the modification of cation exchanger (CAX) activity, given that these transporters are involved in calcium (Ca2+) signaling under stresses. In this study, we used three Brassica rapa mutants (BraA. cax1a-4, BraA.cax1a-7, and BraA.cax1a-12) from the parental line ‘R-o-18’ that were generated by Targeting Induced Local Lesions in Genomes (TILLING) and grown under control and alkaline conditions. The objective was to assess the tolerance of these mutants to alkalinity stress. Biomass, nutrient accumulation, oxidative stress, and photosynthesis parameters were analyzed. The results showed that BraA.cax1a-7 mutation was negative for alkalinity tolerance because it reduced plant biomass, increased oxidative stress, partially inhibited antioxidant response, and lowered photosynthesis performance. Conversely, the BraA.cax1a-12 mutation increased plant biomass and Ca2+ accumulation, reduced oxidative stress, and improved antioxidant response and photosynthesis performance. Hence, this study identifies BraA.cax1a-12 as a useful CAX1 mutation to enhance the tolerance of plants grown under alkaline conditions.Plan Propio de Investigación y Transferencia, University of Granada awarde

Visualización de la fluorescencia de clorofila a: Una demostración práctica

Ali Ahmad – University of Granada - 0000-0001-5530-7374Santiago Atero Calvo – University of Granada - 0000-0001-8446-5515Begoña Blasco León – University of Granada - 0000-0001-8061-5141Safa Selmi – Association of Safeguard of Matmata - University of Gabes - 0000-0002-3389-6806Alessandro Candiani – DNAPhone SRL - 0000-0002-6200-7705Vanessa Martos Núñez – University of Granada - 0000-0001-6442-7968Recepción: 14.11.2022 | Aceptado: 18.11.2022Correspondencia a través de ORCID: Ali Ahmad - 0000-0001-5530-7374Área o categoría del conocimiento: Fisiología Vegetal – DocenciaAbstract: Chlorophylls are the principal components of plants for light harvesting. They utilize the energy retrieved from solar radiations to carry out the process of photosynthesis and produce reduced organic compounds such as carbohydrates. However, all of the incident light is not used in photosynthesis process, it confronts two other fates. A part of it is dissipated as heat, whereas the other is emitted as fluorescence. These processes occur simultaneously and whether one or the other occurs to a greater or lesser extent will depend both on the physiological status of the plant and the environmental conditions it faces. Chlorophyll (Chl) fluorescence is inversely proportional to the yield of photosynthesis and therefore is of prime importance in plant physiology. Furthermore, there are a lot of studies where Chl a fluorescence has been used as a probe for estimating photosynthetic yield, drought, salinity, vigor, and environmental effects on crop production yield. Therefore, this study was undertaken to demonstrate the visualization of the light emitted from Chl, commonly known as Chl a fluorescence. Plant leaves were dark adopted for 20 minutes before their exposure to ultraviolet (UV) light. Red glasses were used to visualize the emitted red light (fluorescence) from the leaves. This study may instill further interest in the plant physiology students to deepen and expand their learning by undertaking simple demonstrations like this.Resumen: Las clorofilas son los principales componentes de las plantas para recolectar la luz. Utilizan la energía procedente de la radiación solar para llevar a cabo el proceso de fotosíntesis y producir moléculas orgánicas reducidas como los hidratos de carbono. Sin embargo, el total de la utilización de la luz incidente no toda es aprovechada en el proceso de fotosíntesis, ya que esta se enfrenta a otros dos destinos. Una parte se disipa como calor, mientras que la otra se emite como fluorescencia. Estos procesos ocurren de forma simultánea y que se de uno u otro proceso en mayor o menor medida, va a depender tanto del estatus fisiológico de la planta como de las condiciones ambientales a las que se enfrente. La fluorescencia de la clorofila (Chl) es inversamente proporcional al rendimiento o la tasa de la fotosíntesis y, por lo tanto, tiene una importancia fundamental en los estudios de fisiología vegetal. Asimismo, hay muchos estudios en los que la fluorescencia de Chl a se ha utilizado como sonda para estimar el rendimiento fotosintético, la sequía, la salinidad, el vigor y los efectos ambientales en la producción y el rendimiento de los cultivos. Por lo tanto, este estudio se realizó para demostrar la visualización de la luz emitida por la Chl, comúnmente conocida como fluorescencia de Chl a. Las hojas de las plantas fueron adoptadas en la oscuridad durante 20 minutos antes de su exposición a la luz ultravioleta (UV). Se utilizaron gafas rojas para visualizar la luz roja emitida (fluorescencia) de las hojas. Este estudio puede infundir más interés en los estudiantes de fisiología vegetal para que profundicen y amplíen su aprendizaje realizando demostraciones sencillas como esta.This work was supported by the projects: “VIRTUOUS” funded from the European Union’s Horizon 2020 Project H2020-MSCA-RISE-2019. Ref. 872181, “SUSTAINABLE” funded from the European Union’s Horizon 2020 Project H2020-MSCA-RISE-2020. Ref. 101007702, and the “Project of Excellence” from FEDER (Fondo Europeo de Desarrollo Regional)- Junta de Andalucía 2018. Ref. P18-H0-4700.University of GranadaAssociation of Safeguard of Matmata - University of GabesDNAPhone SR

CAX1a TILLING Mutations Modify the Hormonal Balance Controlling Growth and Ion Homeostasis in Brassica rapa Plants Subjected to Salinity

Salinity is a serious issue for crops, as it causes remarkable yield losses. The accumulation of Na+ a ects plant physiology and produces nutrient imbalances. Plants trigger signaling cascades in response to stresses in which phytohormones and Ca2+ are key components. Cation/H+ exchangers (CAXs) transporters are involved in Ca2+ fluxes in cells. Thus, enhanced CAX activity could improve tolerance to salinity stress. Using the TILLING (targeting induced local lesions in genomes) technique, three Brassica rapa mutants were generated through a single amino acidic modification in the CAX1a transporter. We hypothesized that BraA.cax1a mutations could modify the hormonal balance, leading to improved salinity tolerance. To test this hypothesis, the mutants and the parental line R-o-18 were grown under saline conditions (150 mM NaCl), and leaf and root biomass, ion concentrations, and phytohormone profile were analyzed. Under saline conditions, BraA.cax1a-4 mutant plants increased growth compared to the parental line, which was associated with reduced Na+ accumulation. Further, it increased K+ concentration and changed the hormonal balance. Specifically, our results show that higher indole-3-acetic acid (IAA) and gibberellin (GA) concentrations in mutant plants could promote growth under saline conditions, while abscisic acid (ABA), ethylene, and jasmonic acid (JA) led to better signaling stress responses and water use e ciency. Therefore, CAX1 mutations directly influence the hormonal balance of the plant controlling growth and ion homeostasis under salinity. Thus, Ca2+ signaling manipulation can be used as a strategy to improve salinity tolerance in breeding programs.PAI program (Plan Andaluz de Investigación, Grupo de Investigación) AGR282National Health and Medical Research Council of Australia German Research Foundation (DFG) FPU14/0185

An Evaluation of the Effectivity of the Green Leaves Biostimulant on Lettuce Growth, Nutritional Quality, and Mineral Element Efficiencies under Optimal Growth Conditions

The use of biostimulants is becoming a useful tool for increasing crop productivity while enhancing nutritional quality. However, new studies are necessary to confirm that the joint application of different types of biostimulants, together with bioactive compounds, is effective and not harmful to plants. This study examined the impact of applying the biostimulant Green Leaves, comprising Macrocystis algae extract and containing a mixture of amino acids, corn steep liquor extract, calcium, and the bioactive compound glycine betaine. The effect of applying two different doses (3 and 5 mL L−1) of this biostimulant was evaluated on lettuce plants, and growth and quality parameters were analyzed along with photosynthetic efficiency, nutritional status, and nutrient efficiency parameters. The application of Green Leaves improved plant weight (25%) and leaf area and enhanced the photosynthetic rate, the accumulation of soluble sugars and proteins, and the agronomic efficiency of all essential nutrients. The 3 mL L−1 dose improved the nutritional quality of lettuce plants, improving the concentration of phenolic compounds and ascorbate and the antioxidant capacity and reducing NO3− accumulation. The 5 mL L−1 dose improved the absorption of most nutrients, especially N, which reduced the need for fertilizers, thus reducing costs and environmental impact. In short, the Green Leaves product has been identified as a useful product for obtaining higher yield and better quality.Funding for open access charge: Universidad de Granada/CBU

Evaluation of Physiological and Quality Parameters of Green Asparagus Spears Subjected to Three Treatments against the Decline Syndrome

Green asparagus (Asparagus officinalis L.) is a widely grown and consumed crop which provides high-level nutritional interest. In recent years, the decline syndrome in asparagus plantations has been rapidly augmenting. This syndrome causes the early death of whole plants, also negatively affecting the new replanting. Decline causes notable economic losses in the sector. The objective of this work was to verify the effect of different treatments against asparagus decline syndrome on the physiological parameters and nutritional quality of the spears. To meet the objective, four different treatments were applied to asparagus plots strongly affected by decline syndrome: (T1) untreated control soil, (T2) biofumigation with Brassica pellets, (T3) biofumigation with chicken manure pellets, and (T4) disinfestation of the soil with Dazomet. The cumulative yield and physiological and quality parameters of green asparagus spears were studied. Thus, malondialdehyde (MDA), photosynthetic pigments, glutathione (GSH), ascorbate (AsA), total phenols, flavonoids, anthocyanin, antioxidant test, mineral nutrients, and the amino acid profile were measured on asparagus spears. The results showed that the Brassica pellets and Dazomet treatments were the most effective against the damage caused by the decline syndrome. However, it would be necessary to monitor the evolution in the following years.INIA and ERDF 2014-2020Project RTA2015-00008-C02,State Training Subprogram of the State Program for the Promotion of Talent and its Employability, at the IFAPA. Grant number [BES-2017-080123].ES

Physiological and Histological Characterization of the <i>ESB1</i> TILLING Mutant of <i>Brassica rapa</i> L.: Potential Use in Biofortification and Phytoremediation Programs

Enhanced suberin1 (ESB1) is a protein whose mutation is correlated with an increase in root suberin and altered nutrient concentrations. Here, we show a physiological and histological characterization of esb1 mutant plants of Brassica rapa L. Therefore, the potential use of this mutant in selenium (Se) biofortification and/or cadmium (Cd) phytoremediation programs was also evaluated by applying 20 μM of Na2SeO4 and 0.49 μM of CdCl2 to a nutrient solution. With respect to wild type (WT) plants, an increase in root suberin was observed in esb1 at the level of the exodermis. This increase in root suberin did not affect photosynthesis performance. However, the esb1 mutant showed an increase in transpiration rate and a decrease in water use efficiency. Additionally, root histological changes affected the transport and concentration of some mineral elements. Thus, our results suggest that esb1 mutants of B. rapa would not be useful for Se biofortification because no significant differences were observed between the two genotypes at the leaf level. Nevertheless, the esb1 mutant reduced Cd translocation to the leaves and increased Fe and Cu uptake, so ESB1 mutation could be useful for Cd phytoremediation and Fe and Cu biofortification, although further research is needed. Therefore, this study provides detailed information on the effect of ESB1 mutation in B. rapa and suggests its potential use in biofortification and phytoremediation programs